Device for loading air with a controllable amount of a granular or powdery material

ABSTRACT

A device for loading a stream of air with a controllable amount of granular or powdery material includes a container for the material. An annular conduit disposed in the free space above the material in the container has nozzles which are operable to discharge compressed air into the container to blow and churn-up the material. A double tube vertically and slidably mounted on the cover of the container is operable to conduct the compressed air to the annular conduit and to receive the air laden with material which has been blown and churned-up by the compressed air discharged into the container by the nozzles on the annular conduit.

BACKGROUND OF THE INVENTION

This invention relates to a device for the loading of air with acontrollable amount of a powdery or fine granular material which iscontained in a container by whirling or churning-up the material, thedevice also being capable of blowing the laden air out of the container.The device is particularly adaptable to load air with powdered magnesiumoxide and to blow the loaded air out of a container into a heatingdevice.

When operating an oil furnace, arrangements have heretofore been made tointroduce into the burner and into the combustion gases a mixture of airand a material such as magnesium oxide in order to prevent in onerespect noxious corrosion of exposed metal parts, and in anotherrespect, to prevent soiling of the boiler, pipe conduits, fittings andexhaust gases.

However, with such arrangements, problems arise because the magnesiumoxide powder is hygroscopic and causes clogging or plugging-up due tothe presence of moisture. The clogging causes disturbances in theaddition of magnesium oxide into the heating system, thereby causingoperating difficulties in the whole combustion system. Devices are knownwhich add the magnesium oxide by using stirring means or othermachanical means and which add the magnesium oxide through acontrollable aperture to an air stream which serves in the movement ofthe powder. These known devices have the disadvantages that theapertures plug up frequently, and continuous and constant blowing in ofpowder into the oil combustion arrangement is not assured. Also thepowder may creep through packings into the mechanical means which mightlead to operating problems. Devices for the whirling-up and blowing-outof powdery materials are also known where such an air stream is blowninto an aperture of a container holding the material, such air streambeing directed against the surface of the powder in order to whirl itup, and where the air stream exits together with the whirled-up materialthrough another aperture.

These known devices do not produce whirling currents energetic enough toeffect reliable dust production out of the powder storage so that thereservoir used with these devices may have a comparatively smallcapacity. Thus heating arrangements having several boilers must befurnished with several individual devices for each boiler, and largeamounts of air are needed in order to raise the dust from the powderedmaterial, a fact which necessitates large blower capacities. Furthermoreno constant intensive raising of dust is obtained in that the loading ofair with equally large amounts of powder is not accomplished when thesurface of the powder in the reservoir sinks slowly, and it is difficultto raise the dust continually when it is all the way down at the bottomof the container and also to blow it out of the container.

Accordingly, an object of the present invention is to overcome thedisadvantages of the known prior art devices by the provision of anarrangement for insuring a continuous, constant, and also controllableraising of dust or powdery material while having a large capacity forthe powder, the device of the present invention making it possible tofurnish large and even extremely large boiler arrangements withmagnesium powder. The aforementioned object is attained, according tothe present invention, by a device having an annular tube or conduitwhich is generally horizontally disposed in the upper free space of acontainer, the container being filled to the extent that some free spacestill remains at its top. The annular tube is disposed at a distanceradially spaced from the cylindrical wall of the container. A pluralityof nozzles are arranged on the annular tube, such nozzles being at leastpartially downwardly directed.

Essentially in the center of the cover of the container, there isarranged an essentially vertical double tube arrangement which isvertically and slidably mounted on the cover. The double tubearrangement carries the aforementioned annular tube. One tube of thedouble tube arrangement is connected at its lower end to the annulartube and is connected at its upper end to a conduit which suppliescompressed air. The other tube of the double tube arrangement passesinto the interior of the container with its lower end disposedsubstantially at or just above the height of the annular tube, thusforming the blow-out conduit for the air laden with the whirled orchurned-up granular or powder material. This arrangement produces astrong whirling stream directed down towards the surface of the materialas well as a whirling stream rotating in the direction of thecircumference of the container. The air stream acts like a tornado orcyclone causing a dusting-up of the powder, and eventually breaks lumpsand large particles by whirling and by knocking them against the wall ofthe container.

The amount of air required for blowing the dust upwardly and for blowingit out may be small, so that the energy requirement for providing thecompression of air may be kept small. It is mainly possible for theblow-head, formed by the annular tube and its nozzles, to follow at aconstant distance the slowly subsiding surface of the powdered material,so that constant raising of dust and loading of the air is obtaineduntil the container is completely emptied. Thus it is possible to workwith constant air pressure so that devices for changing the pressure ofthe air in correlation to the slow emptying of the container are notrequired. It is easy to proportion the amount of the powder which shouldbe blown out, and how much of it should be contained in the air. At acertain constant air pressure the whirled or churned-up amount of powderis larger the closer the blow head is guided towards the surface of thebulk powder in the container. Thus the amount of powder blown out isregulated and kept constant by the speed at which the double tubearrangement, the annular tube, and its nozzles are guided downwardly.For this purpose, preferably the double tube arrangement may be coupledwith a mechanical drive which effects a continual downward motion of thedouble tube arrangement, the speed of such motion being regulated byadjustment of the driving means.

Other features which are considered characteristic of the invention areset forth in the appended claims.

Although the invention is illustrated and described in relationship tospecific embodiments, it is nevertheless not intended to be limited tothe details shown, since various modifications and structural changesmay be made therein without departing from the spirit of the inventionand within the scope and range of equivalents of the claim.

The construction and operation of the invention, however, together withadditional objects and advantages thereof will be best understood fromthe following description of specific embodiments when read inconnection with the accompanying drawings.

SUMMARY OF THE INVENTION

A device for loading a stream of air with a controllable amount ofgranular or powdery material comprises a container having a cover withthe material being disposed in the container and a free space beingprovided between the upper surface of the material and the cover. Anannular conduit having a plurality of nozzles is disposed in the freespace. A double tube means is vertically and slidably mounted on thecover, the double tube means comprising a pair of tubes, one of whichcarries the annular conduit. A connection connects the one tube to asource of compressed air for supplying compressed air to the annularconduit, the other tube having a lower end disposed within the freespace in the container to receive air laden with the material which hasbeen blown and churned-up by the compressed air discharged into thecontainer by the nozzles on the annular conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of a device according to oneembodiment of the invention,

FIG. 2 is a view taken along the line II--II in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings there is shown a cylindrical container 1 whichis filled with a supply of powdery material 2 leaving some free spacethereabove. A horizontally disposed annular tube 4 is located in theupper part of the container 1 above the surface 3 of the powderymaterial 2, the tube 4 being at a comparatively small distance from thewall of the container 1. A plurality of nozzles 5 are disposed on theannular tube 4, as shown in FIGS. 1 and 2, the nozzles are preferablydirected downwardly and towards the sidewalls of the container 1 anddisposed to extend approximately tangentially relative to the annularconduit.

A vertical double tube is disposed at the center of a cover 6 of thecontainer 1. The double tube consists of an external tube 7 and acoaxial internal tube 8. The double tube passes through the cover 6, andis slidably sealed in a stuffing box 9 of the cover 6 such that thedouble tube may slide in a vertical direction while the seal ismaintained. The annular space between the internal tube 8 and theexternal tube 7 serves for the introduction of compressed air and theexternal tube 7 is furnished at its upper closed end with a connector 10serving as an inlet for compressed air. A conduit 11 connects thisannular space at its closed bottom end with the annular tube 4, thelatter being carried by the double tube by the aid of the conduit 11.The interior tube 8 extends with its open bottom end approximately tothe level of the annular tube 4 into the interior container space andserves as the flowing-out conduit in which air, laden with whirled-upmaterial leaves the container 1. A conduit for further transport of themixture of air and the whirled-up powder may be connected to the upperend of the interior tube 8.

The double tube 8 is furnished with a ratchet 12 which meshes with agear 13 of a schematically illustrated driving means 14. The drivingmeans consists of an electrical motor furnished with a reducing drive.The gear 13 is rotated very slowly by an electrical motor whoserotational speed is varied with the aid of, for example, a potentiometerand which may be set at a definite setting or value so that the doubletube together with the annular tube 4, carried by the double tube, sinksslowly and steadily into the container as the powdery material is usedup. Thus the annular tube 4 follows the surface 3 of the powderymaterial down to the compete emptying of the container 1, whereby acontinuous dusting-up of the powdery material and a continuous loadingof the air with powdery material is assured. The amount of air to bewhirled up and to be blown out of the container 1 may be increased ordecreased by regulating the speed of the downward sliding movement ofthe double tube either to a larger or smaller amount.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description and that it will beapparent that various changes may be made in the form, construction, andarrangements of the parts without departing from the spirit and scope ofthe invention or sacrificing all of its material advantages. The formheretofore described being merely a preferred embodiment thereof.

What is claimd is:
 1. A device for loading a stream of air with acontrollable amount of granular or powdery material comprising acontainer having a cover, said material being disposed in said containerwith a free space being provided between the upper surface of saidmaterial and said cover, an annular conduit disposed in a general planewhich is substantially horizontally disposed, said annular conduit beingspaced from the wall of the container and having a plurality of nozzlesdisposed in said free space, said nozzles extending approximatelytangentially relative to said annular conduit, a double tube meansvertically and slidably mounted on said cover, sealing means slidablysealing said double tube means on said cover, driving means for raisingand lowering said double tube means, said double tube means comprising apair of tubes, one of said tubes carrying said annular conduit, aconnection connecting said one tube to a source of compressed air forsupplying conpressed air to said annular conduit, the other tube havinga lower end disposed within said free space in said container, saidlower end of said other tube being disposed substantially aligned withthe center of said annular conduit and at a level substantially at thegeneral plane of said annular conduit to receive air laden with saidmaterial which has been blown and churned-up by the compressed airdischarged into said container by said nozzles on said annular conduit.2. A device according to claim 1 wherein said driving means comprises amotorized drive unit operably engaging said double tube means to effecta continual downward movement of said double tube means according to thelowering of the level of the granular or powdery material in thecontainer.
 3. A device according to claim 1 wherein said nozzles aredownwardly inclined relative to horizontal.